Windows user can't build this lib

#### Expected behavior

build success

#### Actual behavior

build failed, report
```
# github.com/DataDog/zstd
cgo: exec gcc: exec: "gcc": executable file not found in %PATH%
```

because the zstd lib that pulsar-client-go used is a cgo lib

#### Steps to reproduce

build this codes

```go
package main

import (
"fmt"

"github.com/apache/pulsar-client-go/pulsar"
)

func main() {
fmt.Println(pulsar.AUTO)
}
```

#### System configuration
**Pulsar go client version**: v0.6.0
**GO**: 1.16.6

It seems this [lib](https://github.com/klauspost/compress/tree/master/zstd#zstd) doesn't use the cgo, so Windows user can use pulsar-client-go too